Studies on the enzymatically and biologically active products of Bordetella pertussis have been continued. The adenylate cyclase of the organism, which is located primarily in an extracytoplasmic location, is stimulated to increase its activity as much as 1000-fold by a protein found in mammalian erythrocytes, liver, and tracheal mucosa. Two components of B. pertussis cause elevation of circulating insulin levels in mice and rats. Endotoxin is responsible for an early hyperinsullnemia peaking at 8 hours and ending in less than 48 hours. A separate heat-labile factor causes increased insulin levels peaking at 7 days and continuing for several weeks.